"High School Musical" Stars -- Then & Now!

The “High School Musical” star turns 26 -- and the former teen idol has definitely grown up in front of our very eyes.

The California native started his career at age 14, booking a small part on the cult TV show “Firefly.”

By 18, Zac's popularity exploded thanks to his role as Troy Bolton in "HSM," alongside fellow Disney stars Vanessa Hudgens, Ashley Tisdale and Corbin Bleu. He then landed leading roles in “17 Again,” “The Lucky One,” and “The Paperboy.”

Despite all the success, Zac recently completed two stints in rehab for an alleged cocaine addiction earlier this year. He's been seen out since looking happy and healthy -- we’re rooting for you, Zac!

A few of his former Wildcat costars have been in the news recently: Vanessa went wild in "Spring Breakers," Ashley just got engaged and Corbin is currently on "Dancing with the Stars."

Check out the gallery above to see what the rest of the cast is up to now!